基于编码转换的离散演化算法设计与应用

为了利用演化算法求解离散域上的组合优化问题,借鉴遗传算法（GA）、二进制粒子群优化（BPSO）和二进制差分演化（HBDE）中的映射方法,提出了一种基于映射变换思想设计离散演化算法的实用方法——编码转换法（ETM）,并利用一个简单有效的编码转化函数给出了求解组合优化问题的离散演化算法一般算法框架A-DisEA.为了说明ETM的实用性与有效性,首先基于A-DisEA给出了一个离散粒子群优化算法（DisPSO）,然后分别利用BPSO、HBDE和DisPSO等求解集合联盟背包问题和折扣{0-1}背包问题,通过对计算结果的比较表明：BPSO、HBDE和DisPSO的求解性能均优于GA,这不仅说明基于ETM的离散演化算法在求解KP问题方面具有良好的性能,同时也说明利用ETM方法设计离散演化算法是一种简单且有效的实用方法.     

基于改进遗传算法的连续属性离散化方法

粗糙集中的离散化要求在保持原有决策系统的不可分辩关系情况下,用尽量少的断点进行离散化,而求取连续属性值的最优断点集合是一个NP难题.把连续属性值离散化问题作为一种约束优化问题,采用一种改进的遗传算法来获得最优解,并针对离散化问题设计了相应的编码方式和交叉方法.实验结果表明,采用改进的遗传算法求解连续属性值最优断点集合是可行的.     

基于粗糙集的遥感优化分类波段选择

针对高光谱遥感影像的特点,本文采取一种优化分类波段组合的分级选择策略.利用扩展的属性依赖性公式定义了波段间的相似度.通过模糊聚类,得到对原始波段集合的模糊等价划分.在每个模糊等价波段组中,选择一个代表性波段或进行线性融合,完成对原始波段集合的初步降维.基于遗传算法并结合粗糙集理论,绐出两项能提高遗传搜索效率的增效措施,从而对降维后的波段集合进行不一致优化分类波段组合的选择.实验结果表明,本文提出的高光谱遥感影像优化分类波段组合选择方法是非常有效的.     

桁架结构振动的主动模糊控制中主动杆数目与位置优化

研究了采用自适应模糊控制器抑制桁架结构振动时的主动杆数目与位置优化问题.通过定义输入能量相关矩阵优化了主动杆的数目.基于主动杆的控制能量配置准则,给出了主动杆优化配置的模型.研究基于整数编码的遗传算法用于大型离散体中的作动器组合优化问题.最后针对挠性空间智能桁架结构的振动控制仿真,使用基于整数编码的遗传算法(GAs)优化主动杆位置.结果表明对于采用自适应模糊控制律的离散体结构振动控制是行之有效的.     

基于遗传算法的SVM参数组合优化

核函数类型、核函数参数及错误惩罚因子是影响SVM学习能力和泛化能力的关键因素.实际应用中选择上述SVM参数组合多依赖经验或人工尝试,通常很难选择到最优参数组合.提出一种基于遗传算法的SVM优化技术,针对优化对象设计二进制编码基因串和相应遗传算子,能够实现同时对上述三个参数组合的优化.在UCI标准数据库上的实验结果说明了提出方法的有效性.     

一种实现网络k—划分优化的改进遗传算法研究

自动实现网络k-划分优化问题,属于组合优化的范畴。经典遗传算法求解这类问题效率不高。本文运用图的多划分理论对该问题加以分析,同时结合该问题本身的特点提出了一种改进遗传算法,该算法从编码方式、遗传操作、以及参数选取上对经典遗传算法进行了改进。最后将该算法应用到计算机网络的k-划分优化问题中,实际研究结果表明,该算法实现了自动网络划分优化的目的,且算法效率优于经典遗传算法。     

一种求解离散优化问题的粒子群算法

粒子群算法在求解连续变量问题有了比较成功的应用,但是对离散变量问题方面的应用研究却相对滞后.针对离散优化问题,提出了一种遗传粒子群算法.算法使用了交叉、变异等遗传算子替代传统粒子群算法的速度-位移公式,克服了传统粒子群算法对组合优化问题编码时出现的信息冗余的问题,提高了搜索效率.应用该算法求解了车辆路径问题,实验结果表明,该算法具有较好的全局收敛能力和较快的收敛速度.在同等条件下,求解效果要明显好于遗传算法和基于速度位移公式的粒子群算法     

基于遗传算法的虚拟企业局部模型划分方法

局部模型的划分是分解、简化敏捷虚拟企业建立过程决策问题的重要方法，划分结果可能直接影响到敏捷虚拟企业的建立方式、伙伴企业的合作方向和虚拟企业模型的优化,由于该过程涉及到复杂的组合优化问题以及定量评价方法，因此对该问题的求解具有很高难度。本文提出了应用遗传算法为主的算法来优化这一项目划分过程的方法，该方法根据问题的特点采取特定的基因编码、遗传与变异算子等，本文最后依据一个实际算例来说明和验证该算法。     

一种基于进化算法的连续属性离散化方法

连续属性离散化是知识系统中的一个重要环节,一个好的离散化方法能够起到简化知识和描述和便于对知识系统的处理。而求取连续属性值的最优断点集合是一个NP难题,本文把连续属性值离散化问题作为一种约束优化问题,采用遗传算法来获得最优解,并针对离散化问题设计了相应的编码方式、交叉算子和变异算子。实验结果表明,采用遗传算法求解连续属性值最优断点集合是可行的。     

基于二重编码的遗传算法求解连接增强问题

连接增强问题是个组合优化问题,遗传算法适合解决组合优化问题,一般的遗传算法都采用一重编码方法,这里采取二重编码方法来解决连接增强问题,采取了自适应方法来调整交叉和变异概率,模拟实验中比较了二重编码遗传算法和一重编码的遗传算法的性能。     

An oriented spanning tree based genetic algorithm for multi-criteria shortest path problems

This paper investigates an oriented spanning tree (OST) based genetic algorithm (GA) for the multi-criteria shortest path problem (MSPP) as well as the multi-criteria constrained shortest path problem (MCSPP). By encoding a path as an OST, in contrast with the existing evolutionary algorithms (EA) for shortest path problem (SPP), the designed GA provides a “search from a paths set to another paths set” mutation mechanism such that both of its local search and global search capabilities are greatly improved. Because the possibility to find a feasible path in a paths set is usually larger than that of only one path is feasible, the designed GA has more predominance for solving MCSPPs. Some computational tests are presented and the test results are compared with those obtained by a recent EA of which the encoding approach and the ideas of evolution operators such as mutation and crossover are adopted in most of the existing EAs for shortest path problems. The test results indicate that the new algorithm is available for both of MSPP and MCSPP.     

A genetic algorithm for the vendor-managed inventory routing problem with lost sales

This paper proposes a genetic algorithm (GA) for the inventory routing problem with lost sales under a vendor-managed inventory strategy in a two-echelon supply chain comprised of a single manufacturer and multiple retailers. The proposed GA is inspired by the solving mechanism of CPLEX for the optimization model of the problem. The proposed GA determines replenishment times and quantities and vehicle routes in a decoupled manner, while maximizing supply chain profits. The proposed GA is compared with the optimization model with respect to the effectiveness and efficiency in various test problems. The proposed GA finds solutions in a short computational time that are very close to those obtained with the optimization model for small problems and solutions that are within 3.2% of those for large problems. Furthermore, sensitivity analysis is conducted to investigate the effects of several problem parameters on the performance of the proposed GA and total profits.     

Neural network and genetic algorithm-based hybrid approach to expanded job-shop scheduling

The expanded job-shop scheduling problem (EJSSP) is a practical production scheduling problem with processing constraints that are more restrictive and a scheduling objective that is more general than those of the standard job-shop scheduling problem (JSSP). A hybrid approach involving neural networks and genetic algorithm (GA) is presented to solve the problem in this paper. The GA is used for optimization of sequence and a neural network (NN) is used for optimization of operation start times with a fixed sequence.

After detailed analysis of an expanded job shop, new types of neurons are defined to construct a constraint neural network (CNN). The neurons can represent processing restrictions and resolve constraint conflicts. CNN with a gradient search algorithm, gradient CNN in short, is applied to the optimization of operation start times with a fixed processing sequence. It is shown that CNN is a general framework representing scheduling problems and gradient CNN can work in parallel for optimization of operation start times of the expanded job shop.

Combining gradient CNN with a GA for sequence optimization, a hybrid approach is put forward. The approach has been tested by a large number of simulation cases and practical applications. It has been shown that the hybrid approach is powerful for complex EJSSP.     

拉丁超立方体抽样遗传算法求解图的二划分问题

图的二划分问题是一个典型的NP-hard组合优化问题, 在许多领域都有重要应用. 近年来, 传统遗传算法等各种智能优化方法被引入到该问题的求解中来, 但效果不理想. 基于理想浓度模型的机理分析, 利用拉丁超立方体抽样的理论和方法, 对遗传算法中的交叉操作进行了重新设计, 并在分析图二划分问题特点的基础上, 结合局部搜索策略, 给出了一个解决图二划分问题的新的遗传算法, 称之为拉丁超立方体抽样遗传算法. 通过将该算法与简单遗传算法和佳点集遗传算法进行求解图二划分问题的仿真模拟比较, 可以看出新的算法提高了求解的质量、速度和精度.     

混合算法求解多目标平衡旅行商问题

平衡旅行商问题(balanced traveling salesman problem, BTSP)是旅行商问题(traveling salesman problem, TSP)的变化模型,是另一种组合优化问题,可在汽轮机(gas turbine engines, GTE)等的优化问题中得到应用,但BTSP模型只能对含单个旅行商一个任务的优化问题建模,不能同时对含多个旅行商多任务的问题进行建模和优化.基于此,首次提出了一种多目标平衡旅行商问题(multi-objective balanced traveling salesman problem, MBTSP)模型,可建模含多个旅行商多任务的优化问题,具体可应用在含多个目标或个体的实际问题,例如含多个GTE的优化.相关文献的研究已证实,伊藤算法和遗传算法(genetic algorithm, GA)在求解组合优化问题中具有较好的性能,因此,应用混合伊藤算法(hybrid ITO algorithm, HITO)和混合遗传算法来求解MBTSP问题.HITO通过蚁群算法(ant colony optimization, ACO)来产生基于图的概率生成模型,再用伊藤算法的漂移和波动算子对该图模型进行更新,从而得到MBTSP的最优解.对于混合遗传算法,第一个用贪心法对遗传算法进行改进,命名为贪心法遗传算法(genetic algorithm with greedy initialization, GAG),第二个用爬山算法优化遗传算法,称之为爬山法遗传算法(genetic algorithm by hill-climbing, GAHC),最后一个为模拟退火遗传算法(genetic algorithm with simulated annealing, GASA).为了有效验证该算法,使用小尺度到大尺度的不同规模MBTSP问题的数据进行实验,结果表明：混合算法在求解MBTSP问题是有效的,并表现出不同的特点.     

ANSYS优化方法与遗传算法在结构优化方面的比较

以十杆桁架结构重量最轻的优化问题为基础,比较了遗传寻优结果与ANSYS(优化模块使用的是传统的优化方法)优化结果,数据对比分析结果表明,遗传算法在离散变量的结构优化方面比传统方法更容易找到全局性优化解。     

Stacking sequence optimization with genetic algorithm using a two-level approximation

We propose a new method for laminate stacking sequence optimization based on a two-level approximation and genetic algorithm (GA), and establish an optimization model including continuous size variables (thicknesses of plies) and discrete variables (0/1 variables that represent the existence of each ply). To solve this problem, a first-level approximate problem is constructed using the branched multipoint approximate (BMA) function. Since mixed-variables are involved in the first-level approximate problem, a new optimization strategy is introduced. The discrete variables are optimized through the GA. When calculating the fitness of each member in the population of GA, a second-level approximate problem that can be solved by the dual method is established to obtain the optimal thicknesses corresponding to the each given ply orientation sequence. The two-level approximation genetic algorithm optimization is performed starting from a ground laminate structure, which could include relatively arbitrarily discrete set of angles. The method is first applied to cylindrical laminate design examples to demonstrate its efficiency and accuracy compared with known methods. The capacity of the optimization strategy to solve more complex problems is then demonstrated using a design example. With the presented method, the stacking sequence in analytical tools can be directly taken as design variables and no intermediate variables need be adopted.     

基于PSO信息传递模式的混合算法

粒子群优化算法（Particle Swarm Optimization,PSO）是一种基于群智能（Swarm Intelligence）的随机优化计算技术。PSO和遗传算法这两种算法相比较,PSO收敛快速准确,但编码形式单一,局限于解决实优化问题,而遗传算法编码形式灵活,解决问题广泛,但执行效率低于PS00。将粒子群算法的信息传递模式与遗传算法的编码和遗传操作相结合,提出一种混合算法。并推导了两个算法之间的密切联系。并通过组合优化和函数优化的基准测试集对算法进行测试,试验结果表明,该算法在收敛精度和速度优于传统遗传算法。同时,也观察到该算法取得了与粒子群算法一致的收敛现象。     

An effective evolutionary algorithm for the practical capacitated vehicle routing problems

The evolutionary algorithms are extensively adopted to resolve complex optimization problem. Genetic algorithm (GA), an evolutionary algorithm, has been proved capable of solving vehicle routing problems (VRPs). However, the resolution effectiveness of GA decreases with the increase of nodes within VRPs. Normally, a hybrid GA outperforms pure GA. This study attempts to solve a capacitated vehicle routing problem (CVRP) by applying a novel hybrid genetic algorithm (HGA) that is practical for use by manufacturers. The proposed HGA involves three stages. First, a diverse and well-structured initial chromosome population was constructed. Second, response surface methodology (RSM) experiments were conducted to optimize the crossover and mutation probabilities in performing GA. Finally, a combined heuristics containing improved insertion algorithm and random insertion mutation operator was established to stir over gene permutations and enhance the exploration capability of GA diversely. Furthermore, an elitism conservation strategy was implemented that replace inferior chromosomes with superior ones. As the proposed HGA is primarily used to solve practical problems, benchmark problems involving fewer than 100 nodes from an Internet website were utilized to confirm the feasibility of the proposed HGA. Two real cases one for locally active distribution and another for arms part transportation at a combined maintenance facility, both involving the Taiwanese armed forces are used to detail the analytical process and demonstrate the practicability of the proposed HGA for optimizing the CVRP.     

基于GEP的最小二乘支持向量机模型参数选择

针对最小二乘支持向量机的多参数寻优问题,提出了一种基于基因表达式编程的最小二乘支持向量机参数优选方法.该算法将最小二乘支持向量机参数(C,σ)样本作为GEP的基因,按其变异算子随着进化代数和染色体所含基因数目动态变化的机制执行,其收敛速度和精确度大大提高.并与基于粒子群算法和遗传算法参数优选方法比较,通过标准测试函数验证了该算法的拟合误差最低.最后用其建立氧化铝生产蒸发过程参数预测模型,应用工业生产数据进行验证,实验结果表明该方法有效且获得了满意的效果.